initialize doscalar to .false. in mpi{f08} utilities

[hkershaw-brown]

Description:

Please provide a summary of the change and include any relevant motivation and context.

mpi utilties and mpif08 utitlies use countup to "figure out how many items are in the specified arrays, total.
also note if there's more than a single array (array1) to send, and if there are any scalars specified."

The intent(out) doscalar is not set unless a scalar is present. If no scalar is present, doscalar is undefined on return.
This pull request initializes doscalar to .false.

null_mpi_utitiles does not use countup.

Fixes issue

fixes #1169

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Documentation changes needed?

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.

Tests

Please describe any tests you ran to verify your changes.

Checklist for merging

• Updated changelog entry
• Documentation updated
• Update conf.py

Checklist for release

• Merge into main
• Create release from the main branch with appropriate tag
• Delete feature-branch

Testing Datasets

• Dataset needed for testing available upon request
• Dataset download instructions included
• No dataset needed

[mjs2369]

Looks good